Optimizing Fertilizer Use Research Articles

Optimizing fertilizer use efficiency for sustainable maize production in strongly acid soils of the Sudan Savanna agroecological zone of Northern Ghana

Given the importance of maize as a staple crop in northern Ghana, and the prevalence of acid soils used for maize production in the region, identifying effective nutrient management is critical to realize the full benefits of fertilizer application in maize production. In a two-year field study, we evaluated different fertilization strategies in three communities to identify the one that will best optimize fertilizer use efficiency in maize production in poorly fertile acid soils. The fertilization strategies were: (i) farmer practice (FP), in which only NPK fertilizer was applied; (ii) NPK plus lime (NPK + L); (iii) balanced fertilization (BF), in which NPK fertilizer and limiting secondary and micronutrients were applied; (iv) balanced fertilization plus lime (BF + L); and (v) control, in which no fertilizer was applied. We determined maize grain yield, nutrient recovery, and agronomic efficiency and the potential profitability with the fertilization strategies. The greatest yield was obtained with the BF + L treatment, followed by NPK + L, BF, FP, and control, in that order. Compared to FP, the NPK + L treatment nearly doubled N recovery, tripled P recovery, and doubled K recovery from the applied fertilizer. Whereas a negligible increase in fertilizer recovery efficiency occurred with the BF treatment compared to FP; the N, P, and K recovery efficiency increased by nearly 3, 4, and 2.5 times, respectively, with the BF + L treatment compared with FP. Gross profit margin analysis showed that the greatest potential profit margin was obtained with the BF + L treatment, followed by NPK + L, BF, and FP, in that order. From the combined data, we conclude that addition of lime is key to increasing fertilizer efficiency in strongly acid soils, and with a holistic approach of simultaneous addition of lime and secondary and micronutrients to NPK fertilizers, farmers will optimize fertilizer efficiency and increase profitability of their farming operation substantially.

The Role of Balanced Fertilization on the Reduction of Phytic Acid to Zinc Molar Ratio (PA/Zn) in the Irrigated and Rainfed Wheat Fields on the Calcareous Soils of Iran

One of the most important quality factors in the wheat grain, which directly affects the quality of the bread, is the molar ratio of phytic acid to zinc (PA/ Zn) index. In order to evaluate the role of balanced fertilization on increasing the yield, quality, and reducing PA/Zn in wheat grain (Triticum aestivum L.), the first experiment was implemented with two fertilizer treatments (Farmer’s conventional fertilization practice, i.e. NP-fertilizers) and the optimum use of fertilizers (fertilization was on the basis of soil test results) in three different irrigated farms in Mianeh, East Azarbaijan province and the second experiment was carried out in 10 different dryland farms on the outskirts of the Khodabandeh, Zanjan Province in 2010-2011 growing season with an average of 380 mm annual rainfall. This experiment had three treatments, i.e. T1=Control (no fertilizer); T2=Farmer’s conventional fertilization practice (NP-fertilizers), and T3=Fertilization based on soil test values (Optimum use of fertilizers) in four replications with a randomized complete block design. The wheat cultivar in the irrigated farms was Alvand and in the rainfed farms was Azar-2. Protein, phytic acid, phosphorus (P), potassium (K), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu), and Zinc (Zn) in wheat grains were analyzed according to the standard methods. The collected data were analyzed by using a t-test and SAS Software. The results revealed that in the irrigated wheat fields, the optimal use of fertilizers increased the grain yield up to 27 percent, protein content, all micronutrients especially Zn significantly, but it decreased PA/Zn molar ratio significantly in comparison to Farmer’s conventional fertilization practice. While phytic acid concentration in the control plots was 8.70, it decreased up to 7.41gkg-1, Zn concentration was increased from 29 to 43 mgkg-1 and subsequently, PA/Zn molar ratio was reduced from 30 to 17. The statistical analysis showed a significant difference for phytic acid, Zn, and PA/Zn molar ratio in all wheat farms in the second experiment, the results demonstrated that while the average grain yield in T1 was 975kgha-1, it has increased up to 1401kgha-1 in T2 and over 1628kgha-1, respectively. The average yield increase was significant at the 5% level despite the existing drought situation in the fall of 2010. The mean concentration of P and Zn in wheat grains in the control plots were 0.26 percent and 21mgkg-1, in Farmer’s conventional fertilization practice were 0.24 percent and 25mgkg-1 and in the fertilization based on soil test values were 0.21 percent and 30mgkg-1, respectively and they were significant in the 5% level. While PA/Zn in the control plots was 29, it has been decreased to 22 in T2 and to 15 in T3 plots, respectively. Comparison between PA/Zn molar ratios revealed that due to the existing water during the growing season in the irrigated fields, the availability of all nutrients including Zn was slightly higher, but in drylands, the amount and distribution of rainfall is much important and it is clear that by increasing the amount and distribution of rainfall during the growing season, more grain yield and lower PA/Zn molar ratio is expected. It is obvious that these variations are widely dependent on climate change, cultivars, and management factors. This project is recommended to be continued at least in the wheat-grown provinces all over the Iran.

The Role of Balanced Fertilization on the Reduction of Phytic Acid to Zinc Molar Ratio (PA/Zn) in the Irrigated and Rainfed Wheat Fields on the Calcareous Soils of Iran

One of the most important quality factors in the wheat grain, which directly affects the quality of the bread, is the molar ratio of phytic acid to zinc (PA/ Zn) index. In order to evaluate the role of balanced fertilization on increasing the yield, quality, and reducing PA/Zn in wheat grain (Triticum aestivum L.), the first experiment was implemented with two fertilizer treatments (Farmer’s conventional fertilization practice, i.e. NP-fertilizers) and the optimum use of fertilizers (fertilization was on the basis of soil test results) in three different irrigated farms in Mianeh, East Azarbaijan province and the second experiment was carried out in 10 different dryland farms on the outskirts of the Khodabandeh, Zanjan Province in 2010-2011 growing season with an average of 380 mm annual rainfall. This experiment had three treatments, i.e. T1=Control (no fertilizer); T2=Farmer’s conventional fertilization practice (NP-fertilizers), and T3=Fertilization based on soil test values (Optimum use of fertilizers) in four replications with a randomized complete block design. The wheat cultivar in the irrigated farms was Alvand and in the rainfed farms was Azar-2. Protein, phytic acid, phosphorus (P), potassium (K), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu), and Zinc (Zn) in wheat grains were analyzed according to the standard methods. The collected data were analyzed by using a t-test and SAS Software. The results revealed that in the irrigated wheat fields, the optimal use of fertilizers increased the grain yield up to 27 percent, protein content, all micronutrients especially Zn significantly, but it decreased PA/Zn molar ratio significantly in comparison to Farmer’s conventional fertilization practice. While phytic acid concentration in the control plots was 8.70, it decreased up to 7.41gkg-1, Zn concentration was increased from 29 to 43 mgkg-1 and subsequently, PA/Zn molar ratio was reduced from 30 to 17. The statistical analysis showed a significant difference for phytic acid, Zn, and PA/Zn molar ratio in all wheat farms in the second experiment, the results demonstrated that while the average grain yield in T1 was 975kgha-1, it has increased up to 1401kgha-1 in T2 and over 1628kgha-1, respectively. The average yield increase was significant at the 5% level despite the existing drought situation in the fall of 2010. The mean concentration of P and Zn in wheat grains in the control plots were 0.26 percent and 21mgkg-1, in Farmer’s conventional fertilization practice were 0.24 percent and 25mgkg-1 and in the fertilization based on soil test values were 0.21 percent and 30mgkg-1, respectively and they were significant in the 5% level. While PA/Zn in the control plots was 29, it has been decreased to 22 in T2 and to 15 in T3 plots, respectively. Comparison between PA/Zn molar ratios revealed that due to the existing water during the growing season in the irrigated fields, the availability of all nutrients including Zn was slightly higher, but in drylands, the amount and distribution of rainfall is much important and it is clear that by increasing the amount and distribution of rainfall during the growing season, more grain yield and lower PA/Zn molar ratio is expected. It is obvious that these variations are widely dependent on climate change, cultivars, and management factors. This project is recommended to be continued at least in the wheat-grown provinces all over the Iran.

A Sensitive Wavebands Identification System for Smart Farming

Sensing the content of macronutrients in the agricultural soil is an essential task in precision agriculture. It helps the farmers in the optimal use of fertilizers. It reduces the cost of food production and also the negative environmental impacts on atmosphere and water bodies due to indiscriminate dosage of fertilizers. The traditional chemical-based laboratory soil analysis methods do not serve the purpose as they are hardly suitable for site specific soil management. Moreover, the spectral range used in the chemical-based laboratory soil analysis may be of 350–2500 nm, which leads to redundancy and confusion. Developing sensors based on the discovery of spectral wavebands that respond to soil macronutrient concentrations, on the other hand, is an innovative and successful technology since the results are dependable and timely. The goal of this article is to use a supervised neuro-fuzzy based dimensionality reduction approach in the sensor development process to determine sensitive wavebands of soil macronutrients. Accordingly, the spectral signatures of the soil are collected in an outdoor environment and mapped with its macronutrient concentrations. In this spectral analysis, the spectral reflectance of 424 wavelengths has been obtained and these wavelengths are evaluated through combined and individual modes as well. Appropriate wavelengths are selected in each case by minimizing the fuzzy reflectance assessment index. The effectiveness of these selected wavelengths in each mode is validated by modeling the relation between the reduced reflectance space and each macronutrient concentration using Partial Least Squares Multi Variable Regression (PLS-MVR) method. Set of optimal wavebands are identified and the results are compared with the existing systems.

Assessment of Factors that Limit Optimal Use of Organic Fertilizers in Subsistence Food Production in Vihiga County, Kenya

In the face of skyrocketing prices of inorganic fertilizers, organic materials are considered the alternative sources of fertilizers. Research institutions have over the years succeeded in demonstrating high yield responses to recommended usage of organic fertilizers. Furthermore, organic fertilizer (biofertilizers) is a vital component of sustainable agriculture. The sound management of organic fertilization must attempt to ensure both an enhanced and safeguarded environment. Most Farmers in Vihiga County have adopted use of organic fertilizers. Despite this, crop yields remain low in farmers’ fields due to low soil fertility and inability of farmers to optimally use organic fertilizers. Researchers often use optimal organic materials recording high yields in experimental and farm demonstration fields. Little or no research has been done to determine why farmers still record low yields despite a lot of extension outreaches to promote available organic matter technology packages in the study area. This paper reports findings of a study carried out to determine factors that limit optimal use of organic fertilizer by farmers in Vihiga County, Kenya. The objective of the study was to compare organic fertilizer usage in farmers’ field with optimal (recommended) rates to determine if the usage were significantly different. This was aimed at providing advice based on empirical evidence to farmers on whether there is need to improve usages of organic fertilizer and to determine if low intensity of organic fertilizer was a possible cause of recorded low yields in farmers’ fields. Purposive sampling was used to select farmers who were using organic fertilizer for soil fertility. A total of 120 farmers were selected to provide data needed for the study. Primary data was collected using questionnaires and data was analyzed using descriptive statistic (t-test). The results of the analysis indicated a significant difference in the usage between what farmers applied and what was recommended by research. Usages of organic fertilizer among the sampled farmers were much lower than the recommended levels explaining the low maize yields among farmers in the study area. The study rejected the hypothesis that the farmers’ usages of organic fertilizer was not statistically significant different from that recommended by research institutions. This is because average usage of organic fertilizer of 320.3 kg/ha was significantly below those recommended by researcher of 5ton/ha (at 99% usage. Farmers must follow appropriate promoted technology recommendations. The study recommended promotion of organic fertilizer. Farmers should be sensitized on the need to bridge the gap between the current and the recommended usage for them to realize the benefits of organic fertilizer.

Phosphorus flow analysis for megacities using a coupled city-hinterland approach: Case study of Beijing

Rapid urbanization has decoupled phosphorus (P) urban consumption and hinterland production, which has accelerated the need for a broader perspective that includes the city and hinterland in managing the P cycle. However, there is a scarcity of frameworks for the combined city and hinterland approach, aimed at quantifying the transboundary P flow between the city and hinterland. In this study, we developed a coupled city-hinterland framework (using Beijing as a case study) to assess the P flow pattern at the source, waste, and transboundary flow using substance flow analysis, and proposed a pathway to identify the key subsystem in the coupled system by sensitivity analysis. Results shows that the P waste within Beijing is due to human consumption, rather than production, while P waste in the hinterland was nearly twice that observed in Beijing. Further, hinterland crop production subsystems were identified as the key subsystem to reduce P rock demand for the whole coupled system; 39% of P rock demand could be reduced by optimizing fertilizer use in the hinterland. In the scenarios that consider an improvement in technology both in Beijing and its hinterland, 64% and 60% of the total P rock demand and waste were reduced, respectively. Therefore, we provided suggestions to reduce P waste in the coupled system. This study provides a broader perspective to evaluate the impacts of urban consumption on the hinterland, which will serve as a basis for policy decisions for sustainable P flow in the supply chain of other similar cities.

Soil extracellular oxidases mediated nitrogen fertilization effects on soil organic carbon sequestration in bioenergy croplands

AbstractNitrogen (N) fertilization significantly affects soil extracellular oxidases, agents responsible for decomposition of slow turnover and recalcitrant soil organic carbon (SOC; e.g., lignin), and consequently influences soil carbon sequestration capacity. However, it remains unclear how soil oxidases mediate SOC sequestration under N fertilization, and whether these effects co‐vary with plant type (e.g., bioenergy crop species). Using a spatially explicit design and intensive soil sampling strategy under three fertilization treatments in switchgrass (SG: Panicum virgatum L.) and gamagrass (GG: Tripsacum dactyloides L.) croplands, we quantified the activities of polyphenolic oxidase (PHO), peroxidase (PER), and their sum associated with recalcitrant C acquisition (OX). The fertilization treatments included no N fertilizer input (NN), low N input (LN: 84 kg N ha−1 year−1 in urea), and high N input (HN: 168 kg N ha−1 year−1 in urea). Besides correlations between soil oxidases and SOC (formerly published), both descriptive and geostatistical approaches were applied to evaluate the effects of N fertilization and crop type on soil oxidases activities and their spatial distributions. Results showed significantly negative correlations between soil oxidase activities and SOC across all treatments. The negative relationship of soil oxidases and SOC was also evident under N fertilization. First, LN significantly depressed oxidases in both mean activities and spatial heterogeneity, which corresponded to increased SOC in SG (though by 5.4%). LN slightly influenced oxidases activities and their spatial heterogeneity, consistent with insignificant changes of SOC in GG. Second, HN showed trends of decrease in soil oxidase activities, which aligned with the significantly enhanced SOC in both croplands. Overall, this study demonstrated that soil oxidase activities acted as sensitive and negative mediators of SOC sequestration in bioenergy croplands and optimizing fertilizer use particularly in switchgrass cropland can improve for both carbon sequestration and environmental benefit.

Farm Size, Risk Aversion and Overuse of Fertilizer: The Heterogeneity of Large-Scale and Small-Scale Wheat Farmers in Northern China

The excessive use of fertilizer has resulted in serious environmental degradation and a high health cost in China. Understanding the reasons for the overuse of fertilizer is critical to the sustainable development of Chinese agriculture, and large-scale operation is considered as one of the measures to deal with the excessive fertilizer use. Under the premise of fully considering the resource endowment and heterogeneity of large-scale farmers and small-scale farmers in production and management, different production decision-making frameworks were constructed. Based on the 300 large-scale farmers and 480 small-scale farmers in eight provinces of northern China wheat region, we analyzed the optimal fertilizer use amount and its deviation as well as the influencing factors of small-scale and large-scale farmers, then further clarified whether the development of scale management could solve the problem of excessive fertilizer use. The empirical results show that: (1) both small-scale farmers and large-scale farmers deviated from the optimal fertilizer application amount, where the deviation degree of optimal fertilizer application of small-scale farmers is significantly higher than that of large-scale farmers, with a deviation degree of 35.43% and 23.69% for small and large scale farmers, respectively; (2) not all wheat growers in North China had the problem of excessive use of chemical fertilizer, as the optimal level of chemical fertilizer application in Heilongjiang and Inner Mongolia are 346.5 kgha−1 and 335.25 kgha−1, while the actual fertilizer use amount was 337.2 kgha−1 and 324.6 kgha−1, respectively; and (3) the higher the risk aversion level, farmers tended to apply more fertilizer to ensure grain output. Therefore, increasing farm size should be integrated into actions such as improving technological innovation and providing better information transfer to achieve the goal of zero-increase in Chinese fertilizer use.

Resource use efficiency among rice farmers around fragile ecosystems: evidence from Kilombero Wetland, Tanzania

Farmers have been encroaching fragile wetlands as a strategy to increase their rice production thus threatening wetlands’ existence and capacity to other critical ecosystem services. This calls for efficient production to strike the balance between food rice production and wetlands’ sustainable existence. The current study sought to provide assess rice farmers’ technical efficiency of resource use by detecting the determinants of rice yield and further identify the determinants of technical efficiency of the resources used by rice farmers in Kilombero wetland. A cross-sectional survey of 145 randomly sampled farmers aided in achieving the study objective. A stochastic frontier analysis (SFA) model was used to analyze data. The mean technical efficiency among farmers was at 60.54% level. The positive determinants of rice yield were land and fertilizers while labor influenced it negatively. Age, education, farming experience, group membership, and credit access reduced inefficiency while the distance to the extension agent and off-farm income increased farmers’ inefficiency. The study concludes that there is a possibility of expanding rice production without threatening the wetland’s existence. It recommends that government and other stakeholders to ensure that rice farmers are up-to-date with optimal use of fertilizers in rice production since it will assist in improving rice yield while the rate of expansion of rice lands in the wetlands will lower. Policy implementers ought to establish initiatives that inspire rice farmers to capitalize on farmer groups and join education programs to take full advantage of their potential efficiency and might participate in community development activities.
 JEL code: Q15

A Typological Concept to Predict the Nitrogen Release from Organic Fertilizers in Farming Systems

The prediction of nitrogen (N) mineralization or immobilization in organic fertilizers is an important tool to optimize fertilizer use, especially in intensive agricultural systems. Our aim was to derive a model to predict the N mineralization/immobilization from readily available information on the properties of organic fertilizers in farming practice. On the basis of a literature review, a characterization of organic fertilizers was performed, revealing a large variance in fertilizer properties within the defined categories and subcategories. A partial linear model was derived and used for the prediction of N mineralization/immobilization based on the type of fertilizer and the carbon (C) to organic nitrogen (Norg) ratio. Depending on the previously defined category, a strong mineralization (e.g., plant- and animal-based commercial fertilizers) or a predominant immobilization (e.g., compost and slurries) was detected. For a total of seven main categories and their subcategories, individual models were developed. This work shows that the mineralization properties of organic fertilizers can be sufficiently predicted through a simple classification into a fertilizer category and through the C to Norg ratio.

Strategi peningkatan pendapatan petani padi di Kecamatan Gunung Tujuh Kabupaten Kerinci

This study aims to: (1) determine the socio-economic characteristics of rice farmers in Gunung Tujuh District, Kerinci Regency (2) to determine what factors affect the income of rice farmers in Gunung Tujuh Subdistrict, Kerinci Regency (3) to determine strategies for increasing income rice farmers in Gunung Tujuh District, Kerinci Regency. The quantitative analysis used in this research is regression analysis. Based on the results of multiple regressions, working capital variables, land area, and total production have positive and significant coefficients on farmers' income, where the amount of production variable is the variable that has the greatest influence on the income of rice farmers in Gunung Tujuh District, Kerinci Regency. The results of this study in the form of a strategy to increase rice farmers' income based on internal and external results showed that the main strategy is the strategic focus that must be done, namely optimizing weaknesses and overcoming various threats by reducing land conversion by providing capital, reactivating Gapoktan, optimizing fertilizer use, overcoming the problem of increasing input prices to increase cooperation between extension workers and Gapoktan in Gunung Tujuh District, Kerinci Regency.

Integrating fuzzy cognitive maps and multi-agent systems for sustainable agriculture

In conventional agriculture, a wide variety of decisions are made with high uncertainty. Recommendations regarding pesticides, fertilizers, and irrigation water are made in a very generic manner and do not consider the intrafield variability of parameters that can affect crop yields. This has serious economic and environmental implications. The goal of precision agriculture is to improve agricultural sustainability and to optimize crop growth decisions by accounting for field variability and site-specific parameter values. The aim of the present work was to build an online smart platform based on innovative technologies such as multi-agent processing and fuzzy cognitive maps that improves decision-making by farming field-management nodes, which should ultimately save resources at the farm level while increasing the income from farming through the optimal use of both water and fertilizers and respecting the environment and the consumer. The platform helps farmers to access knowledge that can assist them in making the right decisions when implementing precision agriculture management actions (e.g., matching the application of nitrogen to crop demands, predicting key growth stages, and estimating the optimal duration of irrigation).

HYDRUS-1D Simulation of Soil Water Dynamics for Sweet Corn under Tropical Rainfed Condition

Assessment of soil water balance is essential to understand water dynamics for optimal use of water and fertilizers. The study intended to simulate soil water dynamics in sweet corn production under tropical rainfed conditions. Surface runoff, subsurface leaching, and evapotranspiration are the main components of water balance, especially in tropical environments. Therefore, intensive field experiments and HYDRUS-1D numerical modeling were applied to investigate the water balance components and analyzing water dynamics. The study was carried out in a sweet corn field for two growing seasons under the rainfed conditions at the Malaysian Agricultural Research and Development Institute (MARDI), Serdang, Malaysia. The total water inputs during the first and second seasons were 75.8 cm and 79.7 cm, respectively. Simulated results of evapotranspiration (ET) accounted for 40.7% and 33.1% of total water input during the first and second seasons. Surface runoff accounted for 41% and 28.6% in the first and second season, respectively. Water leaching accounted for 10.6%–26.8% of total water input during both seasons respectively. As rainfall fulfilled the crop water requirement throughout the growing seasons no additional irrigation was required. The overall simulation results validate the HYDRUS-1D as an effective tool to simulate soil water dynamics under rainfed conditions.

Validating integrative nutrient diagnostic norms for greenhouse cut-roses

Efforts to optimize fertilizer use efficiency in intensively managed greenhouse rose crops led to studies to establish and validate norms for their integrated nutrient diagnosis. The present study experimentally validates the practical usefulness of previously established DRIS (Diagnosis and Recommendation Integrated System) and CND (Compositional Nutrient Diagnosis) norms for soil-grown roses in the Bogota Plateau of Colombia. Corrective fertilization treatments, based on a control fertigation solution, were designed based on preliminary diagnosis by DRIS methodology, and applied over two growth and flowering flushes in an experimental plot within a commercial rose crop. These integrative nutrient diagnoses methods detected microelement imbalances in rose leaf tissues, including excesses of iron (Fe) and deficiencies of zinc (Zn), copper (Cu) and manganese (Mn). Conventional soil and foliar analyses had some contrasting interpretation diagnoses on these nutrients. Implementation of corrective changes, based on DRIS results, to the supply of these micronutrients in fertilization treatments improved the elemental (individual) and mean nutrient balance indices in rose leaf tissues, and led to gradual increases in average stem length and the fraction of harvested flowers with longer stems (>70 cm) over the course of two flowering cycles. These DRIS and CND methods highlighted a significant Fe:Mn interaction in rose crops, likely affected by the supply and ratio of micronutrients in the fertigation solutions, inherently low Mn levels in the soils of the region, and a major role of the dominant rootstock in use. The use of integrative nutrient diagnosis methods, based on relationships between all nutrient elements and flower yield as the primary response criterion, offer an enhanced capacity to identify those elements with the highest probability of generating a positive flower yield response when correcting their supply in rose fertilization programs.

The Soil Health Card Scheme in India: Lessons Learned and Challenges for Replication in Other Developing Countries

ABSTRACT This article assesses the design, process flow, and impact of the Soil Health Card (SHC) scheme in India, which was introduced in 2015. Under this scheme, government mechanisms distribute SHCs to each farmer. The article examines the scheme using a nationally representative sample of farmers in 2017. Awareness of the SHC scheme among the farmers was high at 82%, but only 66% were able to understand the recommendations, and only 48% followed the recommended rate of fertilizer application. Literacy rates, irrigated area, contact with extension workers, subsidized micronutrients, and the infrastructure index had a positive influence on use of SHCs. The farmers benefited through optimal use of fertilizers and reduced cost of production. To replicate similar schemes in other developing countries, they have to enhance state capabilities in terms of soil sample collection and testing with the latest technologies such as GPS-enabled tablets and mass testing, along with better fertilizer subsidy policies.

Life Cycle Assessment of Cane-sugar in Indonesian Sugar Mill: Energy Use and GHG Emissions

This paper presents the life cycle assessment (LCA) of sugar cane production at PG Ngadirejo, that is consist of sugar cane cultivation, transportation and sugar processing. The objective of the study was to identify and review the critical areas of potential Global Warning Potential (GWP) environmental impacts in sugarcane life cycle on PG Ngadirejo. Energy consumption in the sugarcane life cycle is 116.562.52 MJ/ton sugar where the largest consumption in coal energy usage 87%. The relative contribution of CO2 emission contributor, sugar processing contributes the biggest GHG emission of 96.4% (10.728 ton CO2/ton of sugar) with the use of fossil fuels reaching 9,344 ton CO2/ton sugar (87%). In sugarcane cultivation, fertilizer manufacture contributed the largest environmental impact of 0.29 tons CO2/ton of sugar 73.48%, pesticide manufacture 22.5%, and mechanization 4%. The emission reduction from bagasse that replaces fossil fuels in sugar production is 2.43 tons CO2-eq/ton of sugar, reaching 25% of total CO2/ton sugar emissions. Some options for the environmental performance improvement of sugarcane including the optimal use of fertilizers and pesticides, the concentration of sugar mills, co-generation project implementation.

Responses of residual and recommended N, P, K, S nutrients and crops to six annual soil test-based fertilizer rates and seeding systems

Responses of residual and recommended nitrogen (N), phosphorus (P), potassium (K), sulfur (S) nutrient amounts and crops (yield, emergence, and height) to 0, 60, 100, and 140% soil test-based fertilizer rate applications on the same plots for six years under minimum tillage and direct seeding systems were assessed. Higher fertilizer rates increased residual nitrate (NO3)-N, extractable K, and sulfate (SO4)-S amounts after a low crop yield year, particularly NO3-N, without temporal trend. Increase in residual available P level at higher fertilizer rates showed a positive temporal trend. Lower N, P, and S fertilizer rates were recommended to crops after higher residual NO3-N, available P, and SO4-S levels. Crops effectively used the residual nutrients. Compared to 0%, the relative seed yields at 60, 100, and 140% rates increased with years of fertilization. There were no clear responses of measured soil and crop parameters to seeding systems. Testing residual nutrients can optimize fertilizer use and crop yields.

Mineral Fertilizer and Manure Effects on Leached Inorganic Nitrogen, Nitrate Isotopic Composition, Phosphorus, and Dissolved Organic Carbon under Furrow Irrigation.

A better understanding of nutrient leaching in furrow irrigated agriculture is needed to optimize fertilizer use and avoid contamination of water supplies. In this field study (2003-2006), we measured deep percolation fluxes at 1.2-m depth and associated nutrient concentrations and mass losses from dairy manure nitrogen (N) or mineral N (urea, sodium nitrate [NaNO])-amended soils (372 kg available N ha in 4 yr) and nonamended controls and determined the δN-NO and δO-NO isotope ratios in the leached nitrate. Flow-weighted concentration means for individual irrigations varied widely, from near zero to as much as 250 mg L for NO-N, 480 μg L for dissolved reactive phosphorus (DRP), 43 mg L for dissolved organic C (DOC), and 390 mg L for chloride (Cl). Relative to other treatments, mineral fertilizer increased NO-N concentrations 2.6- to 3-fold and Cl concentrations 2.6- to 3.6-fold in deep leachate, particularly when NaNO was applied in 2004 and 2006, and produced maximum mean season-long NO-N and Cl losses. Manure and control treatments produced similar leachate nutrient mass losses, and for some irrigation periods, mineral fertilizer produced 85 and 97% lesser DRP losses and two times greater Cl losses compared with manure and control treatments. Four-year cumulative losses among treatments differed only for Cl. Isotopic composition of deep-leached nitrate indicates that both transformation and biologic cycling of mineral and manure N are rapid in these soils, which, with percolation volume, influence the amounts of NO-N and DOC leached. In light of the potential negative effects associated with either fertilizer type, and because even nonamended soils produced substantial amounts of leached NO-N (69.5 kg ha yr), management must minimize percolation water losses to limit nutrient losses from these fertilized, furrow-irrigated soils.

Optimizing Fertilizer Use by Smallholder Farmers and Economic Returns to Maize in Semi-arid Niger

Optimizing Fertilizer Use by Smallholder Farmers and Economic Returns to Maize in Semi-arid Niger

Duckweed (Spirodela polyrhiza) as green manure for increasing yield and reducing nitrogen loss in rice production

Increasing rice production to feed the world’s growing population while protecting the environment requires more optimal use of fertilizers. In China, the current high input, high output and high reliance on synthetic nitrogen (N) fertilizer in agriculture has resulted in high N losses, especially ammonia (NH3) emission. Urea combined with green manure (GM) might be a promising approach to improve N fertilizer management. However, few studies have evaluated duckweed in this manner. Duckweed does not require arable land for cultivation and thus avoids competition with food crops. Therefore, a field experiment was conducted for three years with five treatments (CK, no N-fertilizer; CT, conventional practice, urea alone at 300kgNha−1; CTD, urea combined with duckweed at 300kgNha−1; RN, urea alone at 225kgNha−1; and RND, urea combined with duckweed at 225kgNha−1) in an intensive rice cropping system in the Taihu Region of China. The results for two years showed that urea combined with duckweed cover reduced NH3 loss by 36–52% over CT. This reduction was attributed primarily to the formation of a physical barrier and the uptake of NH4+ by duckweed. The 15N recovery for 15N balance conducted for one year was 38% higher and the 15N loss was 16% lower for CTD than that of CT. Furthermore, urea combined with duckweed increased N accumulation in the aboveground plants by 14–25% over CT for the 3 years. As a result, urea combined with duckweed achieved higher rice yield by 9–10%, and higher net economic benefit by 10–11% over CT for the 3 years; however, using the conventional rate of 300kgNha−1 did not increase rice yield over using the reduced N rate of 225kgNha−1, with or without duckweed. Thus, duckweed as GM combined with chemical fertilizer application provided an approach for increasing the rice yield without increasing inputs of N fertilizer and thereby provided a financially attractive option for farmers to achieve environmental integrity and ensure food security in rice production.